One can get an empirical estimate of the unreddened \(F_B\)  vs. \(F_V\)  gradient of a typical low-redshift AGN by considering the bluest variable AGN continua. One cannot simply take the bluest known gradient because extrema are influenced by observational errors. An accurate estimation of the bluest \((B-V)\)  depends on knowing the errors in the gradient estimates, something beyond the scope of this study. However, the 90th percentile of the \(F_B\)  vs. \(F_V\)  gradients of the large [1]} low-redshift sample is 1.18. We will therefore adopt this as the unreddened \(F_B\)  vs. \(F_V\)  gradient. The 80th percentile of the distribution gives 1.12, which suggests the uncertainty in the assumed unreddened slope is of the order of \(\pm 0.06\) . Assuming an intrinsic slope of 1.18 compared with 1.07 raises an estimate of \(E(B-V\)  by \(\sim 0.11\)  magnitudes. [2]} noted that the reddenings they got from the Chołoniewski method were systematically lower that the reddenings implied by the Balmer decrements. Increasing their reddenings from flux-variability gradients by 0.11 magnitudes, as suggested here, removes this systematic difference.
